Discoveries at the edge of the periodic table: First ever measurements of einsteinium. Since element 99 -- einsteinium -- was discovered in 1952 from the debris of the first hydrogen bomb, scientists have performed very few experiments with it because it is so hard to create and is exceptionally radioactive. A team of chemists has overcome these obstacles to report the first study characterizing some of its properties, opening the door to a better understanding of the remaining transuranic elements of the actinide series. Source 5k.